Selective serotonin and norepinephrine

DUAL SELECTIVE SEROTONIN AND NOREPINEPHRINE REUPTAKE INHIBITORS (SSNRIs)... 

Side effects, mainly due to serotonin reuptake inhibition include G1 upset, nervousness, and sexual dysfunction. SSRls are associated with an increased risk of falls. Hyponatraemia due to SIADH is an uncommon, but important side effect in elderly patients. Selective serotonin and norepinephrine reuptake inhibitors (S SNRls) such as venlafaxine and duloxetine are also useful in older patients. Other heterocyclic antidepressants of importance in older patients because of relative safety include bupro-prion and mirtazepine. They are reserved for patients with resistance to or intolerance of SSRls. Currently, trazodone is used mostly for sleep disturbance in depression in doses of 50-100 mg at bedtime. The monoamine oxidase inhibitors phenelzine. 

Post-2000 Renal rhabdomyolysis with the statin, cerivastin cardio-toxicity with the COX-2 inhibitor, rofecoxib and liver damage with the selective serotonin and norepinephrine reuptake inhibitor, atomoxetine. 

Venlafaxine is one of the first selective serotonin and norepinephrine reuptake inhibitors developed for the treatment of depression. It was originally released in the United States in 1994. 

Traditionally, benzodiazepines and tricyclic antidepressants (TCAs) have been the most prescribed drug treatments for GAD. However, selective serotonin reuptake inhibitors (SSRIs), as well as selective serotonin and norepinephrine... 

Harmer, C.J., Shelley, N.C., Cowen, P.J., and Goodwin, G.M. (2004). Increased positive versus negative affective perception and memory in healthy volunteers following selective serotonin and norepinephrine reuptake inhibition. American Journal of Psychiatry, 161, 1256-1263. 

Thiophene seems to be very popular in Li Lilly drugs. Its dual selective serotonin and norepinephrine reuptake inhibitor (SSNRI) for depression, duloxetine (Cymbalta), contains a thiophene. And its atypical antipsychotic drug olanzapine (Zyprexa) has a fused thiophene as its core structure. 

Duloxetine is a selective serotonin and norepinephrine reuptake inhibitor (SNRI). Duloxetine is available as delayed-release capsules for oral route. 

Asymmetric synthesis is also common. Another technique is kinetic resolution. Kinetic resolution relies upon a difference in reactivity between the two enantiomers. For example this technique can be used in the synthesis of duloxetine. Duloxetine is marketed as the hydrochloride salt under the tradename Cymbalta as an antidepressant. It is a selective serotonin and norepinephrine reuptake inhibitor. It is the S enantiomer which is used. 

MAOI, monoamine oxidase inhibitor SARI, serotonin antagonist and reuptake inhibitor SNRI, serotonin and norepinephrine reuptake inhibitor SSRI, selective serotonin reuptake inhibitor TCA, tricyclic antidepressant. 

The biogenic amines are the preferred substrates of MAO. The enzyme comes in two flavors, MAO-A and MAO-B, both of which, like FMO, rely on the redox properties of FAD for their oxidative machinery. The two isoforms share a sequence homology of approximately 70% (81) and are found in the outer mitochondrial membrane, but they differ in substrate selectivity and tissue distribution. In mammalian tissues MAO-A is located primarily in the placenta, gut, and liver, while MAO-B is predominant in the brain, liver, and platelets. MAO-A is selective for serotonin and norepinephrine and is selectively inhibited by the mechanism-based inhibitor clorgyline (82). MAO-B is selective for /1-phcncthylaminc and tryptamine, and it is selectively inhibited by the mechanism-based inhibitors, deprenyl and pargyline (82) (Fig. 4.32). Recently, both MAO-A (83) and MAO-B (84) were structurally characterized by x-ray crystallography. 

When we talk about serotonin-blocking medications, a point of clarification must be made. In most cases, medications do not block overall serotonin activity but instead block the activity at one of the many serotonin receptor types. For example, the antidepressants trazodone, nefazodone, and mirtazapine increase total serotonin activity yet they block certain of the serotonin receptors. Mirtazapine increases both serotonin and norepinephrine activity by interfering with the alpha-2 receptor. By also blocking the serotonin-2 and serotonin-3 receptors, mirtazapine avoids the sexual dysfunction and GI side effects commonly experienced with other serotoninboosting medications. We cannot truly call these serotonin-blocking medications, because they are serotonin-boosting medications that selectively block certain serotonin receptors. 

Imipramine is a TCA with mixed serotonin and norepinephrine properties. Sertraline belongs to the class of antidepressants know as the SSRIs and selectively blocks neuronal reuptake of serotonin. 

The role of endogenous opioid peptides in mood and anxiety is relatively unknown. However, their existence in large concentrations within relevant limbic structures supports the hypothesis (M. S. Gold et al. 1982a). Direct opioid effects reportedly include anxiolysis and mood enhancement. The selective involvement of the opioids alone is unlikely because their activity is interdigitated with several conventional monoamines such as dopamine, serotonin, and norepinephrine. 

Two classes of antidepressants act as combined serotonin and norepinephrine reuptake inhibitors selective serotonin-norepinephrine reuptake inhibitors (SNRIs) and tricyclic antidepressants (TCAs). 

Remission rates are higher with antidepressants or with combinations of antidepressants having dual serotonin and norepinephrine actions, as compared with those having serotonin selective actions. 

Long after their antidepressant properties were observed, the tricyclics were discovered to block the reuptake pumps for both serotonin and norepinephrine, and to a lesser extent, dopamine (Figs. 5 — 16, 6—5, and 6—6). Some tricyclics have more potency for inhibition of the serotonin reuptake pump (e.g., clomipramine) others are more selective for norepinephrine over serotonin (e.g., desipramine, maprotilene, nortriptyline, protriptyline). Most, however, block both serotonin and norepinephrine reuptake. 

The physiological action of antidepressants is not fully understood. However, they are thought to influence the metabolism, reuptake, or selective receptor antagonism of the neurotransmitters serotonin and norepinephrine. The MAOIs cause an increase of the neurotransmitters norepinephrine, serotonin, and dopamine in the brain by inhibiting their breakdown. The SSRIs prevent the reabsorbtion of serotonin, one of the 50-odd neurotransmitters in the brain. 

The serotonin reuptake inhibitors have been shown to be uniquely effective for treating these disorders. Recent studies have focused on fluoxetine and other selective serotonin reuptake-inhibiting drugs, although clomipramine, a mixed serotonin and norepinephrine uptake inhibitor, may be more potent. Fluvoxamine is marketed exclusively for this disorder in the United States. 

Chronic pain patients tend to have concurrent depression however, the antidepressants chosen may not have any pain-relieving properties. Antidepressants that affect one neurotransmitter in the brain, such as selective serotonin reuptake inhibitors have not appeared to be effective in the management of pain in clinical trials. Antidepressants that affect multiple neurotransmitters— namely, serotonin and norepinephrine—have been shown to be effective pain relievers.Two published metaanalyses have shown that tricyclic antidepressants amitriptyline, desipramine, imipramine, and nortriptyline are the most effective treatment for the management of neuropathic pain. ° These publications review the published clinical trial data for all agents available for the management of neuropathic pain. 

This diverse collection has been grouped together mostly because they do not operate as selective serotonin reuptake inhibitors. Instead, each one interacts differently with neurotransmitters that are tied to depression serotonin, norepinephrine, or dopamine. For instance, one of the more popular non-SSRIs, Effexor (venlafaxine), selectively inhibits the uptake of serotonin and norepinephrine, acting on the same molecular machinery as tricyclic antidepressants (TCAs). But, in contrast to TCAs, Effexor shows no affinity for other neurotransmitter receptors and thus has far fewer side effects than the... 

The selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment of depression in the elderly. Compared with tricyciic antidepressants (TCAs), they are much safer in overdose and, for the most part, their side-effects are better tolerated. The antidepressants that have been shown, in controlled studies, to be effective in geriatric major depression are the SSRIs fluoxetine, paroxetine, and sertraline, the TCAs clomipramine and nortriptyline, and the serotonin and norepinephrine reuptake inhibitor (SNRi) venlafaxine. Given that most antidepressants are effective in the elderly, the choice of drug is based on its side-effect profile and its potential to interact with other medications. 

---